Malcorians are a humanoid civilization that originate from their homeworld on planet Malcor III. They do not have individual digits on their hands and feet, like other humanoids. Instead their digits were webbed together, something akin to a mitten. They believe that they are the highest form of life and that their planet was at the center of the universe. Their planet has a unified government led by a chancellor.
In the 2360s, the Malcorians were in the process of developing warp drive and the United Federation of Planets was secretly monitoring their progress. In 2367, William Riker was surgically altered to appear as a Malcorian for such a mission, but was injured and his true species was revealed. After Riker was tortured by a Malcorian opposed to first contact, the Malcorian leader decided that his people were not yet ready to learn of the existence of other species. (TNG episode: "First Contact")
In Q's anti-time future timeline that Jean-Luc Picard experienced, a Malcorian female was serving in Starfleet in the 2390s and was a transporter operator aboard the USS Pasteur. (TNG novelization: All Good Things)